Gist for Medium article about radio button

RadioButton.swift

import UIKit

class RadioButton: UIControl {
	
	var unselectedBackgroundColor: UIColor = .white {
		didSet {
			contentView.backgroundColor = unselectedBackgroundColor
		}
	}

	var borderColor: UIColor = .black {
		didSet {
			contentView.layer.borderColor = (isOn ? selectedColor : borderColor).cgColor
		}
	}

	var selectedColor: UIColor = .blue {
		didSet {
			checkedView.backgroundColor = selectedColor
			contentView.layer.borderColor = (isOn ? selectedColor : borderColor).cgColor
		}
	}

	var isOn: Bool = false {
		didSet {
			updateState()
		}
	}

	private let size: CGFloat = 24
	private let checkedViewSize: CGFloat = 12

	private let contentView: UIView = {
		let view = UIView()
		view.translatesAutoresizingMaskIntoConstraints = false
		view.layer.borderWidth = 1.2
		return view
	}()

	private let checkedView: UIView = {
		let view = UIView()
		view.backgroundColor = .blue
		view.translatesAutoresizingMaskIntoConstraints = false
		return view
	}()

	override init(frame: CGRect) {
		super.init(frame: frame)
		setup()
	}

	required init?(coder: NSCoder) {
		super.init(coder: coder)
		setup()
	}

	private func setup() {
		addSubview(contentView)
		contentView.addSubview(checkedView)

		contentView.layer.cornerRadius = size / 2
		checkedView.layer.cornerRadius = checkedViewSize / 2
	
		updateState()

		NSLayoutConstraint.activate([
			checkedView.centerYAnchor.constraint(equalTo: contentView.centerYAnchor),
			checkedView.centerXAnchor.constraint(equalTo: contentView.centerXAnchor),
			checkedView.widthAnchor.constraint(equalToConstant: checkedViewSize),
			checkedView.heightAnchor.constraint(equalToConstant: checkedViewSize),
			
			contentView.leadingAnchor.constraint(equalTo: leadingAnchor),
			contentView.topAnchor.constraint(equalTo: topAnchor),
			contentView.trailingAnchor.constraint(lessThanOrEqualTo: trailingAnchor),
			contentView.bottomAnchor.constraint(lessThanOrEqualTo: bottomAnchor),
			contentView.widthAnchor.constraint(equalToConstant: size),
			contentView.heightAnchor.constraint(equalToConstant: size)
		])
		
	}

	private func updateState() {
		contentView.backgroundColor = unselectedBackgroundColor
		checkedView.backgroundColor = selectedColor
		contentView.layer.borderColor = (isOn ? selectedColor : borderColor).cgColor
		checkedView.isHidden = !isOn
	}

	override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
		super.touchesEnded(touches, with: event)
		isOn.toggle()
		sendActions(for: .valueChanged)
		
	}

}

RadioButtonsStack.swift

import UIKit

class RadioButtonsStack: UIView {

	private let stackView: UIStackView = {
		let view = UIStackView()
		view.translatesAutoresizingMaskIntoConstraints = false
		view.alignment = .fill
		view.distribution = .fill
		view.axis = .vertical
		view.spacing = 12
		return view
	}()

	private var radioViews = [RadioButtonView]()

	var selectedIndex: Int?

	init() {
		super.init(frame: .zero)
		setup()
	}

	required init?(coder: NSCoder) {
		super.init(coder: coder)
		setup()
	}

	private func setup() {
		addSubview(stackView)
		NSLayoutConstraint.activate([
			stackView.topAnchor.constraint(equalTo: topAnchor),
			stackView.leadingAnchor.constraint(equalTo: leadingAnchor),
			stackView.bottomAnchor.constraint(equalTo: bottomAnchor),
			stackView.trailingAnchor.constraint(equalTo: trailingAnchor)
		])
	}

	func set(_ options: [String]) {
		radioViews.removeAll()
		stackView.removeAllArrangedSubviews()
		
		for (index, text) in options.enumerated() {
			let radioView: RadioButtonView = {
				let view = RadioButtonView()
				view.radioButton.tag = index
				view.radioButton.addTarget(self, action: #selector(radioSelected(_:)), for: .valueChanged)
				view.set(text)
				return view
			}()
			stackView.addArrangedSubview(radioView)
			radioViews.append(radioView)
		}
	}

	@objc private func radioSelected(_ sender: RadioButton?) {
		guard let sender else { return }
		selectedIndex = sender.tag
		
		radioViews.forEach {
			$0.select($0.radioButton.tag == sender.tag)
		}
	}

	class RadioButtonView: UIView {

		let radioButton: RadioButton = {
			let radioButton = RadioButton(frame: .zero)
			radioButton.translatesAutoresizingMaskIntoConstraints = false
			return radioButton
		}()

		let label: UILabel = {
			let label = UILabel()
			label.translatesAutoresizingMaskIntoConstraints = false
			label.numberOfLines = 0
			label.textAlignment = .left
			label.font = .systemFont(ofSize: 18)
			return label
		}()

		let stackView: UIStackView = {
			let view = UIStackView()
			view.translatesAutoresizingMaskIntoConstraints = false
			view.alignment = .center
			view.distribution = .fill
			view.axis = .horizontal
			view.spacing = 16
			return view
		}()

		init() {
			super.init(frame: .zero)
			setup()
		}

		required init?(coder: NSCoder) {
			super.init(coder: coder)
			setup()
		}

		func setup() {
			addSubview(stackView)
			stackView.addArrangedSubview(radioButton)
			stackView.addArrangedSubview(label)
			NSLayoutConstraint.activate([
				stackView.topAnchor.constraint(equalTo: topAnchor),
				stackView.leadingAnchor.constraint(equalTo: leadingAnchor),
				stackView.bottomAnchor.constraint(equalTo: bottomAnchor),
				stackView.trailingAnchor.constraint(equalTo: trailingAnchor),
				radioButton.widthAnchor.constraint(equalToConstant: 30)
			])
		}

		func set(_ text: String) {
			label.text = text
		}

		func select(_ select: Bool) {
			radioButton.isOn = select
		}
	}
}

extension UIStackView {
	func removeAllArrangedSubviews() {
		let removedSubviews = arrangedSubviews.reduce([]) { (allSubviews, subview) -> [UIView] in
			self.removeArrangedSubview(subview)
			return allSubviews + [subview]
		}
		NSLayoutConstraint.deactivate(removedSubviews.flatMap({ $0.constraints }))
		removedSubviews.forEach({ $0.removeFromSuperview() })
	}
}